1. Technical Field
The present invention relates to a control method for an oscillation circuit, a circuit for oscillation, an oscillator, an electronic apparatus, and a moving object.
2. Related Art
A real time clock (RTC) circuit is a circuit including a clocking function and is incorporated in a variety of electronic apparatuses such as a personal computer. In general, the RTC circuit is requested to continue clocking even when a main power supply of an electronic apparatus is disconnected or when main power is not temporarily supplied because of momentary power interruption. JP-A-2009-131129 (Patent Literature 1) discloses a semiconductor device including a backup power supply switching circuit that monitors the voltage of a main power supply, actuates an RTC circuit with a main power supply when the voltage is equal to or higher than a setting voltage, and actuates the RTC circuit with a backup power supply when the voltage is lower than the setting voltage.
However, Patent Literature 1 discloses the technique for monitoring the voltage of the main power supply and switching the use of the main power supply and the use of the backup power supply but does not refer to a relation between an operation state of the RTC circuit and a power supply switching operation. For example, when the power supply switching is performed when the RTC circuit is performing, for example, adjustment of frequency-temperature characteristics of an oscillation circuit section, it is likely that fluctuation of a power supply voltage supplied to the RTC circuit occurs and causes a malfunction in adjustment processing for the frequency temperature characteristics. This problem is not limited to the adjustment processing for the frequency temperature characteristics and is common to a compensating section that performs processing for correcting fluctuation in an oscillation frequency due to some environmental change.